Merge pull request 'Add ArgoCD OAuth2/OIDC provider' (#3) from benvin/argocd-oidc into main

Reviewed-on: #3

config/groups/argocd-admins.yaml

@@ -0,0 +1,3 @@
+# Members of this group get ArgoCD role:admin (mapped in argocd-rbac-cm).
+# Everyone else who logs in via Authentik gets role:readonly.
+name: argocd-admins

config/providers_oauth2/argocd.yaml

@@ -0,0 +1,21 @@
+# OAuth2/OIDC provider + application for the in-cluster ArgoCD
+# (argocd.k8s.syd1.au.unkin.net). client_secret is read from Vault, not committed.
+name: ArgoCD
+authorization_flow: default-provider-authorization-implicit-consent
+invalidation_flow: default-provider-invalidation-flow
+client_type: confidential
+client_id: argocd
+client_secret_vault:
+  mount: kv
+  path: kubernetes/namespace/argocd/default/oauth-credentials
+scope_mappings:
+  - goauthentik.io/providers/oauth2/scope-openid
+  - goauthentik.io/providers/oauth2/scope-email
+  - goauthentik.io/providers/oauth2/scope-profile
+redirect_uris:
+  # Web UI SSO callback.
+  - matching_mode: strict
+    url: https://argocd.k8s.syd1.au.unkin.net/auth/callback
+  # `argocd login --sso` CLI callback (local listener).
+  - matching_mode: strict
+    url: http://localhost:8085/auth/callback

modules/authentik/variables.tf

@@ -40,9 +40,12 @@ variable "providers_oauth2" {
     # Managed identifiers of scope property mappings (e.g.
     # goauthentik.io/providers/oauth2/scope-openid). Resolved to ids.
     scope_mappings = optional(list(string), [])
+    # allowed_redirect_uris is list(map(string)); the API always stores a
+    # redirect_uri_type key, so it must be set here or every plan drifts.
     redirect_uris = optional(list(object({
       matching_mode     = optional(string, "strict")
       url               = string
+      redirect_uri_type = optional(string, "authorization")
     })), [])
     signing_key           = optional(string, null)
     access_token_validity = optional(string, "minutes=10")